Improved bidirectionally decodable Wyner-Ziv video coding

Reverse playback is one of the most common video cassette recording (VCR) functions for video streaming systems. However, the predictive processing techniques employed in traditional hybrid video coding schemes severely complicate the reverse-play operation. In this paper, we enhance our previously proposed bidirectionally decodable Wyner-Ziv video coding scheme which supports both forward decoding and backward decoding. We derive that in our scheme the optimal Lagrangian multiplier for the backward motion estimation should be averagely two times larger than for the forward motion estimation. The new multiplier contributes 0.2 dB gain in average. We propose an optimal P-frame/M-frame selection scheme to improve rate-distortion performance when the video is transmitted over error prone channels. The new scheme outperforms both H.264 and our previous scheme at all tested loss rate, and gain up to 0.55 dB over our previous scheme in low loss rate case.